Method of localizing mine explosions by dust barriers.



0R 1.261.923 ISR 1 I J. S. GRASTY & W. S. RODMANr METHOD OF LOCALIZING MINE EXPLOSIONS BY ousrammefis.

APPLICATION FILED MAY 13, I916- 1 ,261,923, Patented Apr. 9, 1918 after at;

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nmrnn STATES PATENT orrron JOHN SHARSHALL GRASTY AND WALTER SHELDON RODMAN, OF UNIVERSITY, VIRGINIA.

METHOD OF LOCALIZING- MINE EXPLOSIONS BY DUST BARRIERS.

Specification of Letters Patent.

Patented Apr. 9, 1918.

Original application filed October 27, 1915, Serial No. 58,293. Divided and this application filed May 13, 1916. Serial No. 97,379.

To all whom it may concern:

Be it known that we, JOHN SI'IARSHALL GRASTY, a citizen of the United States, and residing at University, in the county of Albemarle and State of Virginia, and WALTER SHELDON RODMAN, a citizen of the United States, and resident of the same place, have invented certain new and useful Improvements in Methods of Localizing Mine Explosions by Dust Barriers, of which the following is a specification.

The Taffanel method of controlling and preventing the propagation of mine explosions consists in launching a mass of rock dust or other finely ground non-inflammable dust into the air blast that always precedes a dust explosion, and to which the possibility of a dust explosion is due.

The air blast, termed by the English the pioneering wave, by its eddying currents mixes the non-inflammable dust with the coal dust, so when the flame of the explosion reaches the dense cloud of dust, in which inert dust greatly predominates, the latter extinguishes the flame by absorbing heat; also, on account of the large amount used, doubtless each particle of coal dust is surrounded by many particles of inert dust, Which thus form a screen between the flame and the coal dust. The flame of the explosion is sometimes immediately extinguished, but a distance of feet or thereabout may be traversed before the inert dust borne by the explosion wave extinguishes all the flame.

It has been proposed to place the inert dust on shelves, by which it will be picked up by the pioneering wave or to place the dust in suitable containers provided with means, actuated by tripping vanes in advance of the containers, for dumping their contents into the passage to be protected. Inasmuch as velocities of the propagation of the explosion are sometimes as low as 100 feet per second, with correspondingly low pressure gradients in front of the explosion, the tripping vanes, which are actuated by the pressures due to air velocities, are not satisfactory or certain in their action.

On the other hand, the velocity of propa gation of the explosion is sometimes as great or greater than 3000 feet per second, so that any system which relies on the pioneering wave to create a dust barrier may at times be too slugglsh 1n 1ts action, and create such a barrier not in advance of the explosion,

be sufliciently sensitive to respond to the heat attendant upon any gas or dust explosion occurring in its vicinity, whereby the dust will be projected into the passage in advance of its pioneering wave.

(6) Prolonging the duration of the time during which the dust is launched, so that while the initiation of the dust barrier may precede the passage of the pioneering wave, additional dust will be fed during,

and if desired, after the passage of such.

wave.

It will be noted that while these two features of our invention are capable of con joint use, they are each capable of use without the other.

We further propose to project and suspend the dust in the passage to be protected, not by the pioneering wave of the explosion, but independent of such wave by forcibly blowing the dust into passage by air pressure otherthan that due to the explosion, the result of which is to create .a dust barrier by filling the passage to be protected by the non-inflammable and non-explosive mixture formed by the gasesand dust injected into such passage, or by the action of the dust of such mixture on the inflammable material previously in such passage.

Our invention, therefore, relates to the method of initiating the release of the inert dust, and of projecting such dust to form a barrier. The novel means herein shown for carrying out the method herein described are not claimed herein, in that the same forms the subject-matter of our prior application Serial No. 58,293, filed Oct. 27, 1915, of which this is a division, filed in response to the requirements of the Patent Oifice, and

in our other application, Serial No. 58,292, also filed Oct. 27, 1915 which has since, on the 19th day of September 1916, issued into Patent No. 1,198,535.

Referring to the accompanying drawings, in which corresponding parts are designated by corresponding marks of reference,

Figure 1 is a diagrammatic plan of a mine equipped to carry out this invention.

Fig. 2 is a sectional view of a dust container adapted for carrying out this invention; and

Fig. 3 is a section of a box barrier adapted for use in carrying out this invention.

Our invention may be carried out by the use of an initiating mechanism by which the occurrence of the explosion calls into play, the release of the dust, and means for releasing and projecting such dust into the passage in advance of the pioneering wave.

The initiating mechanism comprises some suitable form of thermostatic element adapted to be actuated by the heat of an explosion occurring in the vicinity thereof. In the drawing, this takes the form of an easily fusible strip A, forming a part of an electric circuit fed by a suitable source of potential such as the battery B. Such an element or elements may be located at a proper distance or distances in advance of the point where the barrier is to be created, and may be connected to the mechanism for releasing the dust by the wires C.

The dust-releasing and barrier creating mechanism as shown in Fig. 2, comprises one or more receptacles D, located in recesses cut in the walls of the passages of the mine at points where it is deemed advisable to create a dust barrier, and containing inert dust, the exit of dust therefrom being controlled by a proper initiating mechanism such for instance as that before described. In the drawings, the receptacles D are shown as provided with tight fitting covers d, and as terminating at their lower ends in horizontally projecting nozzles E, normally closed by the flap valves 6, and pointing toward the passage. By this construction, the contents of the receptacles are protected against the access thereto of the moist air of the mines from which they might otherwise absorb moisture, causing the dust to cake.

The valves 6, are further shown as held closed by latches F, which are restrained in position to engage them by the action of solenoid magnets G connected by the wires C to the initiating element A. In the construction shown upon the breaking of the circuit through the element A, the weight of the arms 7, of the catches, and of the armatures g of the magnets will release the valves 6.

A pipe H connected with a suitable air compression, enters the base of each receptacle, and terminates in the nozzle E thereof opposite the opening closed by the valve 0 thereof. lVith this construction, it will be seen that when the valve 6 is down, the nozzle E becomes a means for projecting dust in the passage by means of an air blast.

In practice, the pipes H may be connected to the pressure air pipes commonly present in mines, and designated in the drawings at I, although it is obvious that the pipes H may be fed with an inertgas, instead of air, without departing fromfifr invention.

A pipe J leads from the pipe H into the upper part of the receptacle, and serves to create an air pressure upon the top of the dust in the receptacle for the purpose of ejecting the same,

In the operation of the device as described, upon an explosion occurring in the vicinity of a thermostatic element A, the heat thereof causes a rupture of the circuit feeding the solenoid magnets Gr, which drop their armatures and release the valves 6. The internal pressure in the receptacles instantly blow open the valves and the dust is ejected by the air pressure on the top thereof and by the air blast issuing from the pipes H. By the latter blast, the dust is further projected and carried into the passage to create a screen of dust laden air in advance of the pioneering wave of the explosion. It will be noted that in this operation the work of supporting the dust is not due to the velocity of such wave, but is the result of air current fed through the pipes H from the air compressor.

It will be noted that by a proper proportioning of the parts of the apparatus shown, all of the dust contained in the receptacles will not be instantaneously ejected therefrom, but that such projection will continue for an appreciable interval of time, so that when the initiating action is that due to a thermostatic releasing, and the commencement of the projection is in advance of the pioneering wave, the projection will subsist throughout the period such wave is passing opposite to the projecting means, and may even be continued up to the time of the actual passage of the explosion wave, whereby the dust will be projected into the last named Wave itself. This continued projection of dust is a distinguishing fea ture of our invention from the barriers now in use, and embodying one or more shelves or boxes adapted to be simultaneously tripped, whereby the contents of such boxes are instantaneously and simultaneously projected into the passage.

In Fig. 3 we have a construction by which the launching of the dust from box barriers may be prolonged. In this construction the box K containing the dust will in practice be located above the passage, and is divided into three compartments K, K and K, the

compartments K, and K being narrow at the bottom, While the compartment K has a Wide bottom. The box is provided Withdrop bottom K controlled by a latch, which when released bythe solenoid G in the thermostatic circuit C, Will release the bottom. It is unnecessary to describe in detail, the construction of such a barrier as the same is fully described in our aforesaid Patent No. 1,198,535 in which it is specifically claimed. It will be noted, however, that upon the breakin of the thermostatic circuit, the bottom li will drop and the contents of the compartment K will fall into the passage While, due to the restricted bottoms of the compartments K and K the contents thereof will be retarded in their discharge.

Having thus described our invention What We claim and desire to secure by Letters Patent is v 1. The hereinbefore described method of controlling mine explosions, consisting in creating a dust barrier in advance of the pioneering wave of the explosion by projecting and suspending by an air blast inert dust into an explosive mixture.

2. The hereinbefore described method of controlling mine explosions, consisting in creating a barrier by projecting inert material into an explosive mixture in advance of the pioneering Wave and continuing such projection during the passage of such Wave.

3. The hereinbefore described method of controlling mine explosions, which consists in creating a barrier by continually projecting inert material into an explosive mixture during the danger interval.

In testimony whereof We have hereunto signed our names.

JOHN SHARSHALL GRASTY. WALTER SHELDON RODMAN.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. 0. 

